Math Help - Vector question

1. Vector question

Hi
I need help on the following question:
Given the points A(3,2,-1) and B(1,5,2) find the unit vector $\vec b=\frac{b}{|b|}$

I have found out that $a=3i+2j-k$ & $b=i+5j+2k$

P.S

2. Originally Posted by Paymemoney
Hi
I need help on the following question:
Given the points A(3,2,-1) and B(1,5,2) find the unit vector $\vec b=\frac{b}{|b|}$

I have found out that $a=3i+2j-k$ & $b=i+5j+2k$

P.S
$|\mathbf{b}| = \sqrt{1^2 + 5^2 + 2^2}$

$= \sqrt{1 + 25 + 4}$

$= \sqrt{30}$

So $\frac{\mathbf{b}}{|\mathbf{b}|} = \frac{\mathbf{i} + 5\mathbf{j} + 2\mathbf{k}}{\sqrt{30}}$

$= \frac{1}{\sqrt{30}}\mathbf{i} + \frac{5}{\sqrt{30}}\mathbf{j} + \frac{2}{\sqrt{30}}\mathbf{k}$

$= \frac{\sqrt{30}}{30}\mathbf{i} + \frac{\sqrt{30}}{6}\mathbf{j} + \frac{\sqrt{30}}{15}\mathbf{k}$.